PostgreSQL Backups with Docker

Prerequisites:

  1. the project was generated with use_docker set to y.

For brevity it is assumed that will be running the below commands against local environment, however, this is by no means mandatory so feel free switching to production.yml when needed.

Note that the application stack should not necessarily be running when applying any of the instructions below, unless explicitly stated otherwise. For instance, suppose the stack has been down for quite some time or have never even been up yet – rather than starting it beforehand use a single $ docker-compose -f local.yml run --rm <command> with the desired command. By contrast, should you already have your application up and running do not bother waiting for run instruction to finish (they usually take a bit longer due to bootstrapping phase), just use $ docker-compose -f local.yml exec <command> instead; note that any exec command fails unless all of the required containers are running. From now on, we will be using run-style examples for general-case compatibility.

Creating a Backup

To create a backup, run:

$ docker-compose -f local.yml run --rm postgres backup

Assuming your project’s database is named my_project here is what you will see:

Backing up the 'my_project' database...
SUCCESS: 'my_project' database backup 'backup_2018_03_13T09_05_07.sql.gz' has been created and placed in '/backups'.

Keep in mind that /backups is the postgres container directory.

Viewing the Existing Backups

To list existing backups,

$ docker-compose -f local.yml run --rm postgres backups

These are the sample contents of /backups:

These are the backups you have got:
total 24K
-rw-r--r-- 1 root root 5.2K Mar 13 09:05 backup_2018_03_13T09_05_07.sql.gz
-rw-r--r-- 1 root root 5.2K Mar 12 21:13 backup_2018_03_12T21_13_03.sql.gz
-rw-r--r-- 1 root root 5.2K Mar 12 21:12 backup_2018_03_12T21_12_58.sql.gz

Copying Backups Locally

If you want to copy backups from your postgres container locally, docker cp command will help you on that.

For example, given 9c5c3f055843 is the container ID copying all the backups over to a local directory is as simple as

$ docker cp 9c5c3f055843:/backups ./backups

With a single backup file copied to . that would be

$ docker cp 9c5c3f055843:/backups/backup_2018_03_13T09_05_07.sql.gz .

Restoring from the Existing Backup

To restore from one of the backups you have already got (take the backup_2018_03_13T09_05_07.sql.gz for example),

$ docker-compose -f local.yml run --rm postgres restore backup_2018_03_13T09_05_07.sql.gz

You will see something like

Restoring the 'my_project' database from the '/backups/backup_2018_03_13T09_05_07.sql.gz' backup...
INFO: Dropping all connections to the database...
 pg_terminate_backend
----------------------
(0 rows)

INFO: Dropping the database...
INFO: Creating a new database...
INFO: Applying the backup to the new database...
SET
SET
SET
SET
SET
 set_config
------------

(1 row)

SET
# ...
ALTER TABLE
SUCCESS: The 'my_project' database has been restored from the '/backups/backup_2018_03_13T09_05_07.sql.gz' backup.